As people require higher quality of smart life, demand for data processing has grown bigger. Energy consumption on data processing all over the world has reached, on average, hundreds or even thousands of billions of kilowatt-hours (KWHs) per year. A large data center may occupy an area of tens of thousands of square meters. Therefore, both high efficiency and high power density have become key indicators for healthy development of this industry.
Generally speaking, a server, which has a mainboard including data processing chips such as a CPU (Central Processing Unit), chipsets and memory, and power sources thereof as well as necessary peripheral components, is a key unit of the data center. With improvement of processing capacity of the server, the number and integration level of those chips are increased, requiring more space occupation and more power consumption. Accordingly, the power source (also referred to as “mainboard power source” since it is provided at a same mainboard as the data processing chips) supplying power for those chips is expected to have higher efficiency, greater power density and smaller volume, so as to save power consumption and space occupation for the server and, thus the data center. Furthermore, in order to satisfy the greater power density, switching frequency of the power source has become higher and higher.
With the development of the data center, input voltage of the power source at a POL (Point of Load) may be converted from 12V to 48V or even 400V. Output voltage of the POL, however, is generally low. Thus, a high frequency conversion circuit, which typically includes a transformer, is needed to achieve a large in-out-voltage-ratio. Nevertheless, it is difficult to enable a high efficiency in case of high frequency heavy current at the output side. In related art, for example, topology of LLC resonant converter is widely used due to its advantages such as low switching loss, high efficiency and easy extensibility of output power.
With respect to application of output with low voltage and heavy current, multiple transformers, with their high voltage sides being connected in serial and their low voltage sides being connected in parallel, as shown in FIG. 1, are usually adopted. Circuit elements in dashed boxes 61′ and 62′, respectively, may be defined as a circuit unit, while circuit elements in dashed box 63's are defined as high voltage side power devices. As shown in FIG. 2, each circuit unit includes a high voltage side winding 231′ and a low voltage side winding 232′ connected with two switching devices 233′.
FIGS. 3(a) to 3(d) illustrate block diagrams of a power module 7′ with low voltage and heavy current which is well known in the art. As shown in FIG. 3(a), which is a top view, the module includes a multilayer PCB (Printed Circuit Board) carrier 71′; several high voltage side devices, for example, three transformers 72′; and pins 73′ of the module. Herein, each transformer 72′ includes a U-shaped magnetic core consisting of several magnetic columns 74′ (e.g. two magnetic columns), each of which is coupled with a circuit unit. In other words, the power module is provided with six circuit units arranged in plane distribution. Since the multiple individual transformers 72's are provided in the module, however, air-gap control is required separately in their productions, causing bad consistency and low production efficiency.
FIG. 3(b) illustrates a cross section view along the dashed line in FIG. 3(a). As shown in FIG. 3(b), the switching devices 76′ in each circuit unit are provided at upper and lower surfaces, respectively, of the PCB carrier 75′, and windings of the transformer 72′ are implemented via the multilayer PCB.
FIG. 3(c), which is a side view, illustrates pins 73′ of the module and connection between the power module 7′ and a system board 1′. Specifically, the power module 7′ is connected with the system board 1′ through the pins 73′.
FIG. 3(d) illustrates relative position between the magnetic columns and the system board. As shown in FIG. 3(d), the magnetic column 74′ includes several sections perpendicular to the system board 1′, and cover plates 77′ are provided at both ends of each magnetic column 74′. Such sectional design of the magnetic 74′ requires a relatively large volume of the whole power module 7′.
The power module 7′ shown by FIGS. 3(a) to 3(d) is formed with a plane distribution, which may occupy a large area on the system board 1′ and, also, is adverse to improvement of power density. The power module 7′ is electrically connected with the system board 1′ through the pins 73′ which has certain impedance and, thus, may cause additional loss in case of heavy current output. Moreover, heat dissipation of the module is transferred to the system board via the pins 73′. Similarly, a thermal resistance between the module and the system board may increase due to that of the pins 73′, deteriorating heat dissipation of the module.
In view of above, a converter is urgently needed to overcome those defects in conventional art.
The foregoing information is merely disclosed to facilitate understanding of background of the present disclosure. Therefore, the foregoing information may include information not constituting the prior art known to those of ordinary skill in the art.